Hey Adam my rule of thumb is organics inside, chemical ferts outside. The reason for that being is the smell some organic ferts and or soil mixture can a will bring in the racoons,skunks,etc. Although many many people use organic materials through the grow season, which is ideal and have no issues with there plants coming up mysteriously missing.
Planting in a swamp can be real tuff, and can be very devastating if planting directly in the ground.. Can be done though, you must be prepared for some tough digging and haulin soil, be very generous with vermiculite or perlite.. If I dig down 2 feet around the dry part of our swamp water comes up , Not trying to discourage it, just let it be known that for a good crop in a swamp it's work. 5 gallon buckets would be ideal just your plants will not get as big as they could! which in terms means it is not a mature as it could have been, which can lead to a little later harvest, Now if you had 50 blueberry clones I would really consider 5 gallon buckets.
And a tip .. Pot plant roots love airy soil